Does plan b( taken before ovulation date), prolong your normal ovulation date? thanks

Shouldn't: Plan B is basically high dose BCP. The chemicals that clock your ovulation (FSH, LH, etc) come from the pituitary at the base of your brain. Taking BCP's (the active ingredients of Plan B) should not shift time of ovulation. Simple way to monitor ovulation timing is to do basal body temperature curve. Get good thermometer and graph paper. Read up on it!